Method and arrangement in a wireless communication system

ABSTRACT

Method and arrangement in a user equipment for transmitting scheduling requests to a base station. The base station is adapted to serve the user equipment. The user equipment is configured to transmit scheduling requests to the base station only at certain predetermined scheduling request opportunities. The method comprises triggering a scheduling request transmission, transmitting a scheduling request to the base station at the next occurring scheduling request opportunity, starting a scheduling request prohibiting timer and prohibiting any further scheduling request retransmission at future scheduling request opportunities while the scheduling request prohibiting timer is running. Also, a corresponding method and arrangement in a base station are described.

CLAIMING BENEFIT OF PRIOR FILED U.S. APPLICATION

This application is a continuation of U.S. patent application Ser. No.13/380401, filed Dec. 22, 2011, which corresponds to the national-stageentry International Application PCT/SE2010/050113, with an internationalfiling date of Feb. 2, 2010, and which claims the benefit of U.S.Provisional Application No. 61/221,179, filed Jun. 29, 2009.

The contents of all of the preceding are hereby incorporated byreference herein.

TECHNICAL FIELD

The present invention relates to a method and an arrangement in a basestation and a method and an arrangement in a user equipment. Inparticular, it relates to a mechanism for reducing load and interferenceon communication channels when transmitting scheduling requests.

BACKGROUND

Standardization for the fourth Generation (4G) of cellular networks ison going under the name International Mobile Telecommunications Advanced(IMT Advanced). IMT Advanced promises the next generation mobile networkwith high data rates, seamless connectivity and mobile communicationwithin heterogeneous networks.

For many applications, a short access delay plays a crucial role inproviding a good end user performance. IMT Advanced latency requirementsstate that the one way radio access delay between the mobile terminaland the base station should be under 10 ms.

The Long Term Evolution (LTE) network defined by 3rd GenerationPartnership Project (3GPP) provides improved bit rates with lower accessdelays as compared to the older technologies. For Release-8 userequipment units (UEs), the IMT Advanced delay target is reached if theuser equipment unit is scheduled. If the user equipment needs to requestresources, the delay target is not reached.

The access technology of LTE is based on Orthogonal Frequency DivisionMultiplexing (OFDM) in the downlink and Single Carrier FrequencyDivision Multiple Access (SC-FDMA) in the uplink.

In the present context, the expression uplink is used for thetransmission of signals from the user equipment to the base stationwhile the expression downlink is used for transmission of signals in theopposite direction, i.e. from the base station to the user equipment.The base station may further in an LTE environment be referred to as aneNodeB, or eNB.

The resources are allocated either dynamically in 1 ms basis for theuser equipments on both the downlink and the uplink or semi-persistentlyover a longer period than 1 ms. The scheduling of resources is done bythe eNB and it takes into account the user equipment data buffer as wellas radio propagation characteristics of each user equipment.

The standard uplink scheduling procedure in LTE is shown in FIG. 1. Whennew data arrives to the empty user equipment buffer or the data thatbelongs to a higher priority logical channel group than existing data,the user equipment triggers a Buffer Status Report (BSR) to report itsbuffer size. If the user equipment does not have uplink resources totransmit the buffer status report, it triggers a Scheduling Request(SR).

The scheduling request can be sent on a dedicated scheduling requestchannel (D-SR) or on the contention based Random Access Channel (RA-SR).Use of the dedicated scheduling request channel requires that the userequipment is uplink synchronized and that the user equipment has beenassigned a scheduling request channel on the Physical Uplink ControlChannel (PUCCH). The dedicated scheduling request resource is assignedwith Radio Resource Control (RRC) protocol having a periodicity withcurrent values of 5, 10, 20, 40 and 80 milliseconds in LTE Release-8. InLTE Release-9, even shorter values than 5 milliseconds, are possible.When the eNB has received the scheduling request, it can schedule theuser equipment and transmit an initial grant. Using the initial grant,the user equipment can finally transmit the buffer status report withit.

In summary, before the user equipment is scheduled, multiple steps haveto be taken. This increases the access delay in the uplink. When beingin uplink synchronized, the scheduling request periodicity in PUCCH isone of the biggest contributors in delay increase. To obtain bestperformance of certain applications, the scheduling request periodicityshould be selected to very short value.

In the 3GPP TS 36.321 MAC specification, V8.6.0, the scheduling requestis pending from the time when it is trigged until the time when it iscancelled. The scheduling request is cancelled when uplink schedulingresources are available for a new transmission.

When the scheduling request is pending, during every subframe when theuser equipment unit has valid scheduling request resources on PUCCH, theuser equipment unit instructs the physical layer to signal schedulingrequest. This leads to the physical transmission of the schedulingrequest. In the example depicted in FIG. 1, the scheduling requestperiodicity is fixed to 5 ms and the first opportunity to transmit thescheduling request on PUCCH is in subframe t0. After the eNB hasreceived the scheduling request, a typical processing time of 3 ms isassumed before the user equipment unit is scheduled and the grant istransmitted. The user equipment unit has a next scheduling requestopportunity in 5 ms later, at t1. Because the user equipment unit hasnot cancelled the scheduling request yet, it will retransmit it. As aresult, configuring the scheduling request periodicity to 5 ms leads tophysical transmission of the scheduling request at least twice. Thisgenerates a significant unnecessary load on PUCCH.

The mechanism that the transmission of scheduling requests is prohibitedis known as well as configuration of such mechanism by the network, seeWO 2009038381 A2 METHOD OF RESTRICTING SCHEDULING REQUEST FOR EFFECTIVEDATA TRANSMISSION. However, in WO 2009038381 A2, the only mentionedcondition when the transmission of scheduling request is prohibited iswhen the uplink synch, i.e., Time Alignment timer is expected to expiresoon or when the overall number of scheduling request transmissions hasexceeded a certain number. The idea of WO 2009038381 A2 is instead tostart random access if scheduling request is prohibited.

SUMMARY

It is therefore an object of the present invention to provide amechanism for improving the performance in a wireless communicationsystem.

According to a first aspect of the present invention, the object isachieved by a method in a user equipment for transmitting schedulingrequests to a base station. The base station is adapted to serve theuser equipment. The user equipment further comprises a schedulingrequest transmission trigger and is configured to transmit schedulingrequests to the base station. However, the scheduling requests aretransmitted only at certain predetermined scheduling requestopportunities. The method comprises starting the scheduling requesttransmission trigger. Also, a scheduling request is transmitted to thebase station at the next occurring scheduling request opportunity as aresponse to the started trigger. Further, a scheduling requestprohibiting timer, comprised in the user equipment, is started when thescheduling request is transmitted to the base station for the firsttime. In addition, any further scheduling request retransmission atfuture scheduling request opportunities are prohibited while thescheduling request prohibiting timer is running.

According to a second aspect of the present invention, the object isachieved by an arrangement in a user equipment for transmittingscheduling requests to a base station. The base station is adapted toserve the user equipment. The user equipment further comprises ascheduling request transmission trigger and is configured to transmitscheduling requests to the base station. However, the schedulingrequests are transmitted only at certain predetermined schedulingrequest opportunities. The arrangement comprises a scheduling requesttransmission trigger. The scheduling request transmission trigger isconfigured to trigger a scheduling request transmission. Also, thearrangement comprises a transmitter. The transmitter is configured totransmit a scheduling request to the base station at the next occurringscheduling request opportunity as a response to the started trigger. Inaddition, the arrangement further also comprises a scheduling requestprohibiting timer. The scheduling request prohibiting timer isconfigured to start when the scheduling request is transmitted and toprohibit any further scheduling request retransmission at futurescheduling request opportunities while the scheduling requestprohibiting timer is running.

According to a third aspect of the present invention, the object isachieved by a method in a base station for assisting a user equipment intransmitting scheduling requests to the base station. The base stationis adapted to serve the user equipment. The user equipment is configuredto transmit scheduling requests to the base station only at certainpredetermined scheduling request opportunities. The method comprisesdetermining a factor k to be transmitted to the user equipment, enablingthe user equipment to calculate a scheduling request prohibiting timerlength. Further, the method also comprises transmitting the determinedfactor k to the user equipment. In addition, the method furthercomprises scheduling the user equipment when a scheduling request isreceived from the user equipment.

According to a fourth aspect of the present invention, the object isachieved by an arrangement in a base station for assisting a userequipment in transmitting scheduling requests to the base station. Thebase station is adapted to serve the user equipment. The user equipmentis configured to transmit scheduling requests to the base station onlyat certain predetermined scheduling request opportunities. Thearrangement comprises a determination unit. The determination unit isconfigured to determine a factor k to be transmitted to the userequipment in order for the user equipment to calculate a schedulingrequest prohibiting timer length. Further, the arrangement comprises atransmitter. The transmitter is configured to transmit the determinedfactor k to the user equipment. Additionally, the arrangement comprisesa scheduler. The scheduler is configured to schedule the user equipmentwhen a scheduling request is received from the user equipment.

By starting a scheduling request prohibit timer when the user equipmenthas transmitted the scheduling request on PUCCH first time, the load onPUCCH can be reduced significantly. Further, by configuring schedulingrequest prohibit timers for different user equipments with differentlengths, the retransmissions of scheduling requests are distributed intime as well. Thus the performance of the wireless communication systemis improved.

Other objects, advantages and novel features of the invention willbecome apparent from the following detailed description of theinvention.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is described in more detail with reference to attacheddrawings illustrating exemplary embodiments of the invention and inwhich:

FIG. 1 is a schematic block diagram illustrating communication within aprior art wireless communication system.

FIG. 2 is a schematic block diagram illustrating embodiments of awireless communication system.

FIG. 3 is a combined signalling and flowchart illustrating radio signaltransmission according to some embodiments.

FIG. 4A is a combined signalling and flowchart illustrating radio signaltransmission according to some embodiments.

FIG. 4B is a combined signalling and flowchart illustrating radio signaltransmission according to some embodiments.

FIG. 5 is a flow chart illustrating embodiments of a method in a userequipment.

FIG. 6 is a schematic block diagram illustrating embodiments of a userequipment arrangement.

FIG. 7 is a flow chart illustrating embodiments of a method in a basestation.

FIG. 8 is a schematic block diagram illustrating embodiments of a basestation arrangement.

DETAILED DESCRIPTION

The invention is defined as a method and an arrangement in a userequipment and a method and an arrangement in a base station, which maybe put into practice in the embodiments described below. This inventionmay, however, be embodied in many different forms and is not to beconsidered as limited to the embodiments set forth herein; rather, theseembodiments are provided so that this disclosure will be thorough andcomplete, and convey the scope of the invention to those skilled in theart.

Still other objects and features of the present invention may becomeapparent from the following detailed description considered inconjunction with the accompanying drawings. It is to be understood,however, that the drawings are designed solely for purposes ofillustration and not as a definition of the limits of the invention, forwhich reference is to be made to the appended claims. It is further tobe understood that the drawings are not necessarily drawn to scale andthat, unless otherwise indicated, they are merely intended toconceptually illustrate the structures and procedures described herein.

FIG. 2 depicts an exemplary wireless communication system 100, such ase.g. the IMT Advanced, E-UTRAN, LTE, LTE-Adv, 3rd Generation PartnershipProject (3GPP) WCDMA system, Global System for Mobilecommunications/Enhanced Data rate for GSM Evolution (GSM/EDGE), WidebandCode Division Multiple Access (WCDMA), Worldwide Interoperability forMicrowave Access (WiMax), or Ultra Mobile Broadband (UMB), just tomention some few arbitrary possible options.

The wireless communication system 100 comprises a base station 28 and auser equipment 30, adapted to communicate with each other over at leastone radio channel, within a cell. It will be appreciated that thewireless communication system 100 typically may comprise numerous othernodes, such as other base station nodes and, in some embodiments, othernodes such as control nodes and the like. Only a strictly limitedselection of nodes 28, 30 are shown in FIG. 2 for sake of simplicity.

The base station 28 may be referred to as e.g. a NodeB, an evolved NodeB (eNode B, or eNB), a base transceiver station, Access Point BaseStation, base station router, or any other network unit capable tocommunicate with the user equipment 30 within the cell, depending e.g.of the radio access technology and terminology used. In the rest of thedescription, the term “base station” will be used for the base station28, in order to facilitate the comprehension of the present methods andarrangements.

The base station 28 comprises one or more transceivers which is/areconfigured to transmit a frame of information for transmission over aradio interface. For downlink transmission to the user equipment 30, thetransceiver/s feed plural antennae which function to provide pluralsub-carriers. The transceiver/s thereby transmits symbols of thesubframes of the frame on the downlink on plural sub-carriers in afrequency domain.

The base station 28 may also comprise a base station frame handler,according to some embodiments. The subframe handler may be configured toprepare or format the frame of information for transmission bytransceiver/s on a downlink to the user equipment 30. The optional basestation frame handler has access to or may in some implementationscomprise resource manager/scheduler. The resource manager/schedulermaintains and allocates resources for the user equipment 30 and otheruser equipment units (not illustrated) and schedules resources. One ofthe types of resources which is supervised by resource manager/schedulerare Physical Uplink Control Channel (PUCCH) resources. The PUCCH carriesuplink control information and supports multiple formats.

The user equipment 30 may be represented by e.g. a wirelesscommunication terminal, a mobile cellular phone, a Personal DigitalAssistant (PDA), a wireless platform, a laptop, a computer or any otherkind of device capable to communicate wirelessly with the base station28.

The user equipment 30 shown in FIG. 2 may comprise transceiver/s. Thetransceiver/s may comprise or be connected to user equipment antennas.The user equipment 30 may also comprise a user equipment frame handler,according to some embodiments. The wireless terminal frame handler mayreceive and process downlink subframes and may prepare and format uplinksubframes. At least one of the uplink subframes prepared by userequipment frame handler and transmitted by transceiver/s from userequipment 30 to base station 28 carries the Physical Uplink ControlChannel (PUCCH).

The user equipment 30 may also comprise a scheduling request prohibittimer which is configured and serves to prohibit the user equipment unit30 from transmitting the scheduling request too early after the previousscheduling request attempt.

In the following, the present methods and arrangements are furtherelaborated with specific reference to IMT-Advanced systems and moreparticularly with respect to the uplink in IMT-Advanced, i.e. for thelink from the user equipment 30 to the base station 28. However, it isobvious to a skilled person that corresponding concepts could also beapplied in other wireless communication systems 100.

The present methods and arrangements provide a scheduling requestprohibit timer, which is started when the user equipment 30 hastransmitted a scheduling request on PUCCH to the base station 28 for thefirst time. The idea of the scheduling request prohibit timer is toprohibit the user equipment 30 to transmit the scheduling request tooearly after the previous scheduling request attempt.

Thereby may the load on PUCCH be reduced significantly, as redundantscheduling requests are not transmitted. Further, according to someembodiments, scheduling request prohibit timers for different userequipment 30 may be configured with different timer lengths. Therebyretransmissions of scheduling requests from different user equipment 30are distributed in time, such that collision between user equipmenttransmissions may be avoided.

FIG. 3 is a combined signalling and flowchart illustrating radio signaltransmission between the user equipment 30 and the base station 28,according to some embodiments. The purpose of this illustration is toprovide a general overview of the present methods and thefunctionalities involved. Also, the general purpose and an exemplaryenvironment in which the present methods and arrangements may beimplemented are illustrated.

Data is received in the user equipment buffer. The reception and/ordetection of data to transmit in the user equipment buffer triggers thetransmission of a scheduling request SR to the base station 28. Thescheduling request SR is used for requesting uplink scheduling resourcesfor transmission of the received/detected data.

However, the user equipment 30 is only allowed to transmit schedulingrequests SR at certain predetermined scheduling request opportunitiest0, t1, t2, t3, t4, . . . , t∞. There may be an infinite number ofpossible predetermined scheduling request opportunities t0, t1, t2, t3,t4, . . . , t∞, or a limited number of scheduling request opportunitiest0, t1, t2, t3, t4, . . . , t∞, wherein too is limited to t-max,according to different embodiments.

Thus a scheduling request SR has been triggered, due to received data inthe user equipment buffer. In the illustrated example in FIG. 3, thetriggered scheduling request SR is not allowed to be transmitted untilthe next possible scheduling request opportunity t0. Thereby thescheduling request SR is to be considered as pending until it iscancelled.

All pending scheduling requests SR may be cancelled and schedulingrequest prohibit timer may be stopped when a data is assembled and thisdata comprises a buffer status report which comprises buffer status upto the last event that triggered a buffer status report, or when theuplink grant can accommodate all pending data available fortransmission.

If the user equipment 30 has no valid PUCCH resource for transmitting ascheduling request SR configured in any predetermined scheduling requestopportunities t0, t1, t2, t3, t4, . . . , t∞ a Random Access proceduremay be initialised and all pending scheduling requests may be cancelled.Otherwise, if the user equipment 30 has a valid PUCCH resource forscheduling requests SR at least some predetermined scheduling requestopportunities t0, t1, t2, t3, t4, . . . , t∞, and no scheduling requestprohibit timer 40 is running, the generated scheduling request SR may betransmitted at the next scheduling request opportunity t0.

When the triggered scheduling request SR is transmitted at t0 on PUCCH,the scheduling request prohibit timer 40 is started. The schedulingrequest prohibit timer 40 is comprised in the user equipment unit 30.When the scheduling request prohibit timer 40 is running, the userequipment unit 30 is not allowed to retransmit the scheduling requestSR. According to some embodiments, the user equipment 30 may set thescheduling request prohibit timer 40 to 0 (zero), when a schedulingrequest SR is triggered and there is no other scheduling request SRpending.

When the scheduling request prohibit timer 40 is expired, the userequipment unit 30 is allowed to re/transmit the scheduling request SR onPUCCH again. The timer 40 is stopped when it expires, except when theuser equipment unit 30 cancels the scheduling request SR, when also thescheduling request prohibit timer 40 may be stopped.

The scheduling request prohibit timer 40 may according to someembodiments be set to zero when it is initiated and then incremented foreach passing time unit until a predetermined max timer value is reached.According to some embodiments however, the scheduling request prohibittimer 40 may be set to a predetermined max timer value when initiatedand then counted down to zero, or alternatively to any otherpredetermined minimum timer value is reached.

As long as the scheduling request prohibit timer 40 is running, thescheduling request SR is not resent. In the illustrated example in FIG.3, the scheduling request SR is cancelled in t1, t2 and t3.

When the base station 28 receives the scheduling request SR from theuser equipment 30, the base station 28 schedules the user equipment 30.Thereby a grant may be generated and transmitted to the user equipment30, such that the user equipment 30 may be allocated resources foruplink transmission of the data received in the user equipment buffer.

When the user equipment 30 receives the grant, the data is transmittedto the base station 28 at the allocated resources.

FIG. 4A is a combined signalling and flowchart illustrating radio signaltransmission according to some embodiments.

FIG. 4A illustrates use of the scheduling request prohibit timer 40 whenthe grant is received in a subframe and the scheduling request prohibittimer 40 stopped when the scheduling request SR cancelled. In otherwords, in FIG. 4A the scheduling request prohibit timer 40 prohibits theuser equipment 30 from transmitting the scheduling request SR twice. Thescheduling request prohibit timer 40 is stopped when the schedulingrequest SR is cancelled. If a new scheduling request SR is triggeredafter stopping the scheduling request timer, the user equipment 30 isallowed to transmit the scheduling request SR again.

FIG. 4B is a combined signalling and flowchart illustrating radio signaltransmission according to some embodiments.

In the illustration of FIG. 4B the scheduling request prohibit timer 40expires before the scheduling request SR is cancelled. That is, thescheduling request prohibit timer 40 prohibits the user equipment unit30 from transmitting the scheduling request SR at subframe t1 and t2.The scheduling request prohibit timer 40 is stopped when it expires.After expiration of the scheduling request prohibiting timer 40, theuser equipment 130 is allowed to transmit the pending scheduling requestSR again.

Thus, if the SR prohibit timer 40 has expired and there is still pendingscheduling requests SR, they are allowed to be retransmitted. If the SRprohibit timer 40 is stopped due to cancellation of scheduling requestsSRs, then there is no pending scheduling requests SRs, but when a newtriggered scheduling request SR arrives, that may be transmitted, andthe SR prohibit timer 40 may be started again etc.

A negative side of the scheduling request prohibit timer 40 is that ifthe scheduling request SR is missed by the base station 28, there-attempt is delayed. To avoid too long delays in the case of missedscheduling requests SR, the scheduling request prohibit timer 40 may notbe too long according to some embodiments. On the hand, introducing thescheduling request prohibit timer 40 may decrease the load on PUCCH andthus the need for the retransmission of a scheduling request SR issmaller.

In addition to avoiding unnecessary scheduling requests SR and thusloading PUCCH too much, the scheduling request prohibit timer 40 couldbe utilized in spreading the re-attempts of missed scheduling requestsSR in the time domain. Consider that two user equipment units located inthe neighbouring cells transmit the scheduling request SR on the samePUCCH resource at the same time. Due to interference, the base station28 in the corresponding cells may cannot detect which user equipment 30was transmitting the scheduling request SR and thus do not schedule anyof the user equipment 30. If these two user equipment units have thesame scheduling request periodicity, they make the retransmissions ofthe scheduling requests SR at the same time leading to high interferenceagain. If these two user equipment units would have different schedulingrequest prohibit timer lengths, then the correlation in the interferencewith the lag of scheduling request periodicity may be avoided.

The scheduling request prohibit timer 40 can take various exampleembodiments and have differing implementations. The following arepossible non-limiting and non-exhaustive example implementations and/orconfigurations.

Example Implementation 1

The scheduling request prohibit timer length may be fixed to some commonvalue such as e.g. 10 ms or the length of scheduling requestperiodicity.

Example Implementation 2

The scheduling request prohibit timer 40 has a fixed length and it isconfigured by the base station 28 with RRC. The possible value could bek multiplied with the scheduling request periodicity, where k may besignalled by RRC. Having 4 different possible values of k=0, 1, 2, 3 maygive flexibility to the base station 28 to decide how it would like theuser equipment 30 to behave, according to some embodiments.

Example Implementation 3

The scheduling request prohibit timer length can be, for example, (k+1)multiplied with the scheduling request periodicity, where k isconfigured by the base station 28 and the l is random part selected bythe user equipment 30 ranging between [0, 1, . . . , m]. An exampleproper value for m could be 4, according to some embodiments.

Example Implementation 1 may be the simplest solution to avoidunnecessary scheduling requests SR. Example Implementation 2 may providemore flexibility to base station 28 to configure different userequipment 30 with different values and thus avoid reattempts ofscheduling requests SR at the same time. It is also a way of handlingthe trade-off between avoiding unnecessary reattempts and increasingdelay for necessary reattempts, where the trade-off might be seendifferently for different services. Finally, having a random part in thescheduling request prohibit timer 40 as is proposed in ExampleImplementation 3, the interference between neighbouring cells due tocolliding re-attempts of scheduling requests SR could be reduced.

The base station 28 thus may configure the scheduling request prohibittimer 40 so that the user equipment 30 does not transmit an unnecessaryscheduling request SR on PUCCH just after the previous attempt. In thisway the load on PUCCH can be reduced and unnecessary interferenceavoided. In addition, having a random part, the scheduling requestprohibit timer 40 enables the scheduling request SR retransmissionattempts of different user equipment 30 to occur at different time.

FIG. 5 is a flow chart illustrating embodiments of method steps 501-506performed in a user equipment 30 for transmitting scheduling requests SRto a base station 28. The base station 28 is configured to serve theuser equipment 30. The user equipment 30 comprises a scheduling requesttransmission trigger 620. Further, the user equipment 30 is configuredto transmit scheduling requests SR to the base station 28 only atcertain predetermined scheduling request opportunities t0, t1, t2, t3,t4, . . . , t∞.

The base station 28 and the user equipment 30 are comprised in awireless communication system 100. The wireless communication system 100may be e.g. an IMT Advanced or LTE radio network and the base station 28may be e.g. an evolved node B, eNB, according to some embodiments.

The user equipment 30 comprises a scheduling request prohibiting timer40.

To appropriately transmit scheduling requests SR to the base station 28,the method may comprise a number of method steps 501-506.

It is however to be noted that some of the described method steps areoptional and only comprised within some embodiments. Further, it is tobe noted that the method steps 501-506 may be performed in a somewhatdifferent chronological order and that some of them, e.g. step 502 andstep 503, or even all steps may be performed simultaneously or in analtered or rearranged chronological order. The method may comprise thefollowing steps:

Step 501

This step is optional and may only be comprised within some embodiments.

The scheduling request prohibiting timer 40 may be configured with ascheduling request prohibiting timer length, such that the schedulingrequest prohibiting timer 40 expires when the configured schedulingrequest prohibiting timer length has passed, after having started thescheduling request prohibiting timer 40.

Step 502

The scheduling request transmission trigger 620 is started. Thereby is ascheduling request transmission triggered, which scheduling request SRis to be sent at the next occurring scheduling request opportunity t0,t1, t2, t3, t4, . . . , t∞ when the user equipment 30 is allocatedresources to transmit the scheduling request SR.

The scheduling request transmission trigger 620 may be started whenthere is data in the user equipment buffer to send, according to someembodiments.

Step 503

A scheduling request SR is transmitted to the base station 28 at thenext occurring scheduling request opportunity t0, t1, t2, t3, t4, . . ., t∞. The scheduling request SR is transmitted as a response to thestarted trigger 620.

Step 504

The scheduling request prohibiting timer 40 comprised in the userequipment 30 is started. The scheduling request prohibiting timer 40 isstarted when the scheduling request SR is transmitted to the basestation 28 for the first time.

The scheduling request prohibiting timer 40 may be configured to a fixedscheduling request prohibiting timer length, according to someembodiments.

The scheduling request prohibiting timer 40 may be configured to ascheduling request prohibiting timer length, equal to the time betweentwo scheduling request opportunities t0, t1, t2, t3, t4, . . . , t∞multiplied with a factor k, such that:Scheduling request prohibiting timer length=k·(t2−t1).

According to some embodiments may the scheduling request prohibitingtimer 40 be configured to a scheduling request prohibiting timer lengthwhich is equal to the time between two scheduling request opportunitiest0, t1, t2, t3, t4, . . . , t∞ multiplied with the result of the factork operated by a random variable l, such that:Scheduling request prohibiting timer length=(k+l)·(t2−t1).

The factor k may optionally be received from the base station 28. Therandom variable l may be randomly generated by the user equipment 30.

The factor k may be ranging between zero and infinity such that: k=[0,1, . . . , ∞], wherein the factor k may be transmitted via RadioResource Control (RRC) from the base station 28, and wherein thescheduling request SR may be transmitted on a Physical Uplink ControlChannel (PUCCH).

Step 505

Any further scheduling request retransmission are prohibited at anyfuture scheduling request opportunity t0, t1, t2, t3, t4, . . . , t∞while the scheduling request prohibiting timer 40 is running, i.e. isnot stopped.

Thereby, by not resending scheduling requests SR, the traffic load onthe channel reduced, which leads to an overall improved capacity withinthe wireless communication network 100.

Step 506

This step is optional and may only be comprised within some embodiments.

The scheduling request prohibiting timer 40 is stopped when thescheduling requests SR are cancelled, or when the scheduling requestprohibiting timer 40 is expired.

FIG. 6 schematically illustrates an arrangement 600 in a user equipment30. The user equipment 30 is configured for performing the method steps501-506 for transmitting scheduling requests SR to a base station 28.The base station 28 is adapted to serve the user equipment 30. The userequipment 30 is configured to transmit scheduling requests SR to thebase station 28 only at certain predetermined scheduling requestopportunities t0, t1, t2, t3, t4, . . . , t∞. The base station 28 andthe user equipment 30 are comprised in a wireless communication system100. The wireless communication system 100 may be e.g. an IMT Advancedor a LTE radio network. The base station 28 may be e.g. an evolved nodeB, eNB, according to some embodiments.

In order to perform the method steps 501-506 correctly, the userequipment arrangement 600 comprises a plurality of units such as e.g. ascheduling request transmission trigger 620. The scheduling requesttransmission trigger 620 is configured to trigger a scheduling requesttransmission. Further, the user equipment arrangement 600 comprises atransmitter 630. The transmitter 630 is configured to transmit ascheduling request SR to the base station 28 at the next occurringscheduling request opportunity t0, t1, t2, t3, t4, . . . , t∞, as aresponse to the triggered scheduling request transmission. Also,additionally, the arrangement 600 comprises a scheduling requestprohibiting timer 40. The scheduling request prohibiting timer 40 isconfigured to start when the scheduling request SR is transmitted firsttime and to prohibit any further scheduling request retransmission atfuture scheduling request opportunities t0, t1, t2, t3, t4, . . . , t∞,while the scheduling request prohibiting timer 40 is running, i.e. isnot stopped.

According to some embodiments, the arrangement 600 may further comprisea configuring unit 610. The optional configuring unit 610 is adapted toconfigure the scheduling request prohibiting timer 40 with a schedulingrequest prohibiting timer length, such that the scheduling requestprohibiting timer 40 expires when the configured scheduling requestprohibiting timer length has passed, after having started the schedulingrequest prohibiting timer 40. The configuring unit 610 may receive thescheduling request prohibiting timer length from the base station 28,according to some embodiments. However according to some embodiments thescheduling request prohibiting timer length may be predetermined, orcalculated based on a scheduling request prohibiting timer lengthreceived from the base station 28.

Further, according to some embodiments the arrangement 600 may comprisea receiver 44. The receiver 44 is configured for receiving signals fromthe base station 28.

According to some embodiments, the arrangement 600 may optionallycomprise a buffer 640. The buffer 640 is configured to receive andcontain data, to be transmitted.

In further addition, the arrangement 600 may comprise a transmitter 630.The transmitter 630 is configured to transmit signals e.g. to the basestation 28, according to some embodiments.

Also, furthermore, the arrangement 600 may comprise a frame handler 46.The frame handler 46 is configured to receive and process the downlinksubframes and prepare and format the uplink subframes.

Optionally, the arrangement 600 further also may comprise a processor660. The processor 660 may be represented by e.g. a Central ProcessingUnit (CPU), a processing unit, a microprocessor, or other processinglogic that may interpret and execute instructions. The processor 660 mayperform all data processing functions for inputting, outputting, andprocessing of data including data buffering and device controlfunctions, such as call processing control, user interface control, orthe like.

It is to be noted that any internal electronics of the user equipment 30and/or the user equipment arrangement 600, not completely necessary forunderstanding the present method according to the method steps 501-506has been omitted from FIG. 6, for clarity reasons. Further, it is to benoted that some of the described units 40-660 comprised within thearrangement 600 in the user equipment 30 are to be regarded as separatelogical entities but not with necessity separate physical entities. Tomention just one example, the receiver 44 and the transmitter 630 may becomprised or co-arranged within the same physical unit, a transceiver,which may comprise a transmitter circuit and a receiver circuit, whichtransmits outgoing radio frequency signals and receives incoming radiofrequency signals, respectively, via an antenna. The radio frequencysignals transmitted between the base station 28 and the user equipment30 may comprise both traffic and control signals e.g. pagingsignals/messages for incoming calls, which may be used to establish andmaintain a voice call communication with another party or to transmitand/or receive data, such as SMS, e-mail or MMS messages, with a remoteuser equipment.

The method steps 501-506 in the user equipment 30 may be implementedthrough one or more processors 660 in the user equipment 30, togetherwith computer program code for performing the functions of the presentmethod steps 501-506. Thus a computer program product, such as e.g. acomputer program storage medium, may comprise instructions forperforming the method steps 501-506 in the user equipment 30 and maytransmit scheduling requests SR to the base station 28.

The physical and tangible computer program product mentioned above maybe provided for instance in the form of a data carrier carrying computerprogram code for performing the method steps according to the presentsolution when being loaded into the processor 660. The data carrier maybe e.g. a hard disk, a CD ROM disc, a memory stick, an optical storagedevice, a magnetic storage device or any other appropriate medium suchas a disk or tape that can hold machine readable data. The computerprogram code can furthermore be provided as program code on a server anddownloaded to the user equipment 30 remotely, e.g. over an Internet oran intranet connection.

Further, a computer program product comprising instructions forperforming at least some of the method steps 501-506 may be used forimplementing the previously described method in the user equipment 30for transmitting scheduling requests SR to a base station 28, when thecomputer program product is run on a processor 660 comprised within theuser equipment 30.

FIG. 7 is a flow chart illustrating embodiments of method steps 701-703performed in a base station 28 for assisting a user equipment 30 intransmitting scheduling requests SR to the base station 28. The basestation 28 is adapted to serve the user equipment 30. The user equipment30 is configured to transmit scheduling requests SR to the base station28 only at certain predetermined scheduling request opportunities t0,t1, t2, t3, t4, . . . , t∞. The base station 28 and the user equipment30 are comprised in a wireless communication system 100. The wirelesscommunication system 100 may be e.g. an IMT Advanced/LTE/LTE-Advancedradio network and the base station 28 may be e.g. an evolved node B,eNB, according to some embodiments.

To appropriately assist the user equipment 30 in transmitting schedulingrequests SR to the base station 28, the method may comprise a number ofmethod steps 701-703. It is to be noted that the method steps 701-703may be performed in a somewhat different chronological order and thatsome of them may be performed simultaneously or in an altered orrearranged chronological order. The method may comprise the followingsteps:

Step 701

A factor k to be transmitted to the user equipment 30, enabling the userequipment 30 to calculate a scheduling request prohibiting timer length,is determined.

Step 702

The determined factor k is transmitted to the user equipment 30.

Step 703

The user equipment 30 is scheduled when a scheduling request SR isreceived from the user equipment 30.

FIG. 8 schematically illustrates an arrangement 800 in a in a basestation 28. The arrangement 800 is configured to perform the methodsteps 701-703. Thus the base station arrangement 800 is configured toassist a user equipment 30 in transmitting scheduling requests SR to thebase station 28.

The base station 28 is adapted to serve the user equipment 30. The userequipment 30 is configured to transmit scheduling requests SR to thebase station 28 only at certain predetermined scheduling requestopportunities t0, t1, t2, t3, t4, . . . , t∞. The base station 28 andthe user equipment 30 are comprised in a wireless communication system100. The wireless communication system 100 may be e.g. an IMT Advancedor LTE radio network and the base station 28 may be e.g. an evolved nodeB, eNB, according to some embodiments.

In order to perform the method steps 701-703, the arrangement 800comprises a plurality of units such as e.g. a determination unit 810.The determination unit 810 is configured to determine a factor k to betransmitted to the user equipment 30 in order for the user equipment 30to calculate a scheduling request prohibiting timer length. Further thearrangement 800 comprises a transmitter 820. The transmitter 820 isconfigured to transmit the determined factor k to the user equipment 30.Additionally, the arrangement 800 comprises a scheduler 38. Thescheduler 38 is configured to schedule the user equipment 30 when ascheduling request SR is received from the user equipment 30.

Further, optionally according to some embodiments, the base stationarrangement 800 may comprise a receiver 805. The receiver 805 may beconfigured to receive a signal from the user equipment 30. Also,according to some embodiments, the arrangement 800 may comprise ascheduling request prohibit timer configuring unit 42.

Optionally, the arrangement 800 further also may comprise a processor840. The processor 840 may be represented by e.g. a Central ProcessingUnit (CPU), a processing unit, a microprocessor, or other processinglogic that may interpret and execute instructions. The processing unit840 may perform all data processing functions for inputting, outputting,and processing of data including data buffering and device controlfunctions, such as call processing control, user interface control, orthe like.

It is to be noted that any internal electronics of the base station 28and/or the base station arrangement 800, not completely necessary forunderstanding the present method according to the method steps 701-703has been omitted from FIG. 8, for clarity reasons. Further, it is to benoted that some of the described units 38-840 comprised within thearrangement 800 in the base station 28 are to be regarded as separatelogical entities but not with necessity separate physical entities. Tomention just one example, the receiver 805 and the sender 820 may becomprised or co-arranged within the same physical unit, a transceiver,which may comprise a transmitter circuit and a receiver circuit, whichtransmits outgoing radio frequency signals and receives incoming radiofrequency signals, respectively, via an antenna. The radio frequencysignals transmitted between the base station 28 and the user equipment30 may comprise both traffic and control signals e.g. pagingsignals/messages for incoming calls, which may be used to establish andmaintain a voice call communication with another party or to transmitand/or receive data, such as SMS, e-mail or MMS messages, with anyremote user equipment.

The present mechanism for assisting a user equipment 30 in sendingscheduling requests SR may be implemented through one or more processors840 in the base station arrangement 800 depicted in FIG. 8, togetherwith computer program code for performing the method steps 701-703 ofthe present solution. The program code mentioned above may also beprovided as a computer program product, for instance in the form of adata carrier carrying computer program code for performing the presentsolution when being loaded into the base station 28. One such carriermay be in the form of a memory stick. It is however feasible with otherdata carriers. The computer program code may furthermore be provided asprogram code on a server and downloaded to the base station 28 remotely.

When using the formulation “comprise” or “comprising” it is to beinterpreted as non-limiting, i.e. meaning “consist at least of”. Thepresent invention is not limited to the above described preferredembodiments. Various alternatives, modifications and equivalents may beused. Therefore, the above embodiments are not to be taken as limitingthe scope of the present invention, which is defined by the appendingclaims.

The invention claimed is:
 1. A method in a user equipment fortransmitting scheduling requests to a base station, the user equipmentis configured to transmit scheduling requests to the base station onlyat certain predetermined scheduling request opportunities, the methodcomprising: triggering a scheduling request transmission; transmitting,on a Physical Uplink Control CHannel (PUCCH) resource, a schedulingrequest to the base station at the next occurring scheduling requestopportunity as a response to the triggering; receiving, from the basestation, a factor k; calculating a length of time for a schedulingrequest prohibiting timer based on the factor k received from the basestation; starting the scheduling request prohibiting timer, comprised inthe user equipment, when the scheduling request is transmitted to thebase station; and prohibiting any further scheduling requestretransmission at future scheduling request opportunities while thescheduling request prohibiting timer is running; wherein the schedulingrequest prohibiting timer is configured to a scheduling requestprohibiting timer length which is equal to the time between twoscheduling request opportunities multiplied with the factor k, suchthat:scheduling request prohibiting timer length=k*(t2−t1).
 2. The methodaccording to claim 1, comprising the further step of: stopping thescheduling request prohibiting timer when the scheduling requesttransmission trigger is cancelled or when the scheduling requestprohibiting timer is expired.
 3. The method according to claim 1,comprising the further step, to be performed before the other steps:configuring the scheduling request prohibiting timer with a schedulingrequest prohibiting timer length, such that the scheduling requestprohibiting timer expires when the configured scheduling requestprohibiting timer length has passed, after having started the schedulingrequest prohibiting timer.
 4. The method according to claim 1, whereinthe scheduling request prohibiting timer is configured to use a fixedscheduling request prohibiting timer length.
 5. The method according toclaim 1 wherein the scheduling request prohibiting timer is configuredto use a scheduling request prohibiting timer length which is equal tothe time between two scheduling request opportunities multiplied withthe result of the factor k operated by a random variable l, such that:scheduling request prohibiting timer length=(k+l)*(t2−t1).
 6. The methodaccording to claim 5 wherein the random variable l is randomly generatedby the user equipment.
 7. The method according to claim 5, wherein thefactor k is ranging between zero and infinity such that: k=[0, 1, . . ., ∞], wherein the factor k is transmitted via Radio Resource Control(RRC) from the base station.
 8. A user equipment apparatus fortransmitting scheduling requests to a base station wherein the apparatusis configured to transmit scheduling requests to the base station onlyat certain predetermined scheduling request opportunities the apparatuscomprising: a scheduling request transmission trigger configured totrigger a scheduling request transmission; a transmitter, configured totransmit, on a Physical Uplink Control CHannel (PUCCH) resource, ascheduling request to the base station at the next occurring schedulingrequest opportunity as a response to the triggered scheduling requesttransmission; and a scheduling request prohibiting timer, configured tostart when the scheduling request is transmitted and to prohibit anyfurther scheduling request retransmission at future scheduling requestopportunities while the scheduling request prohibiting timer is running;wherein the user equipment is configured to receive, from the basestation, a factor k, and calculate a length of time for the schedulingrequest prohibiting timer based on the factor k received from the basestation; wherein the scheduling request prohibiting timer is configuredto use a scheduling request prohibiting timer length which is equal tothe time between two scheduling request opportunities multiplied withthe factor k, such that:scheduling request prohibiting timer length=k*(t2−t1).
 9. The apparatusaccording to claim 8, wherein the apparatus is configured to stop thescheduling request prohibiting timer when the scheduling requesttransmission trigger is cancelled or when the scheduling requestprohibiting timer is expired.
 10. The apparatus according to claim 8,wherein the apparatus is configured to: configure the scheduling requestprohibiting timer with a scheduling request prohibiting timer length,such that the scheduling request prohibiting timer expires when theconfigured scheduling request prohibiting timer length has passed, afterhaving started the scheduling request prohibiting timer.
 11. Theapparatus according to claim 8, wherein the scheduling requestprohibiting timer is configured to use a fixed scheduling requestprohibiting timer length.
 12. The apparatus according to claim 8 whereinthe scheduling request prohibiting timer is configured to a schedulingrequest prohibiting timer length which is equal to the time between twoscheduling request opportunities multiplied with the result of thefactor k operated by a random variable l, such that:scheduling request prohibiting timer length=(k+l)*(t2−t1).
 13. Theapparatus according to claim 12, wherein the apparatus is configured torandomly generate the random variable l.
 14. The apparatus according toclaim 12, wherein the factor k ranges between zero and infinity suchthat: k=[0, 1, . . . , ∞], and wherein the apparatus is configured toreceive the factor k via Radio Resource Control (RRC) from the basestation.